Resilient member



Patented Jan. 8, 1929.

UNITED STATES PATENT oEEIcE.v j

EARL 'VICTOR JOHNSON, OF HINSDALE, ILLINOIS, ASSIGNOR- TO WESTERN ELCTRIC i COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

RESILIENT MEMBER.

Application led April 13, 1927. Serial No. 183,440.

This invention relates to resilient. members and methods of pretensioning said members, and more particularly to electrical contact elements and methods of producing a prede- 6 termined tension in such elements.

In certain types of apparatus and particularly in various classes of electrical .apparatus, resilient parts, such as metallic contact springs and the like, are employed to open and close electrical circuits. Thus, for

example, in telephone exchange systems, electro-magnetic devices or relays are employed which comprise a plurality of metal contact springs mounted and arranged in parallel- 16 ism which are operable to control telephone circuits in response to'current How through the relay winding. The eiiicient functioning of these springs is dependent to a large degree upon their resilient properties and the tension of each spring should be such as to Apermit the yielding thereof upon the -application of a predetermined force and in some instances to cause a spring to exert a definite contact pressure.

The primary object of this invention is to provide resilient members having a `predetermined tension, when in place, and simple and effective methods of producing a predetermined tension in such resilient members.

In accordance with the general features of the invention, one embodiment thereof consists in the production of electrical contact springs provided on. one, surface with a series of spaced alterations or depressions of Varied sizes extending transversely thereof, the

depressions constituting each series being arranged in graduated order along the surface according to their respective sizes with the depression of greatest size or extent positioned nearest the fixed end of the springs. The general arrangement or distribution and therelative sizes of the depressions, which arestamped upon the surface of the springs by the use of dies, are governed by the required amount of tension necessary for the eiiicient functioning of the individual springs.

These and other objects will be apparent from the following detailed description taken in connection with the accompanying drawings, whereinl Figs. 1 and 2 are elevational views of a relay ofthe type employed in telephone circuits which is equipped with contact springs embodying the features of the invention;

Fig. 3 is a` fragmentary, elevational view of the relay-disclosing the reverse side of the relay shown in Fig. 1; v j

Fig. 4 is an enlarged, fragmentary view partly in section of the relay contact springs and die members associated therewith;

Fig. 5 is a perspective view of the lowermost ldie member shown in Fig. 4;

Fig. 6 is'a'transverse, sectional View taken on the line 6-6 of Fig. 2, and

Fig. 7 is a transverse, sectional view taken on the line 7--7 of Fig. 2.l

Referring now to the drawing wherein like numeralshave been employed to designate similar parts throughout .the various figures, it will be observed that for the purposes of illustrating one embodiment of the invention, an electro-magnetic device or relay 10 is shown which comprises a group of contact springs denoted generally by the numeral 11 disposed on opposite sides of a relay winding 13. One extremity of a core 14 which .supports the winding 13 provides a mounting for the groups of contact springs, ythe springs in each group being insulated from the core as well as from each other and secured in superimposed positions by means of suitable screws 16. An armature 17 (Figs. 2 and 4) is hinged at the end adjacent the mounted portions of the spring by means of a suitable leaf spring 19, and this armature is adapted to be swung downwardly about the hinge.19 from its position shownin Fi l 2 when the relay is vsufliciently energize The downward swinging of th'e armature 17 causes the contact point of a spring 20 of the group 11 to become disengaged from a spring 21-and contemporaneously therewith a spring 23 is carried into engagement with a contact point carried by an adjacent spring 24. When the relay winding 13 is 'de-energized, the Contact springs will again return to their normal positions as shown in Fig. 2.

, From the foregoing it will be clear that the eiicient cooperation between the various contact springs will depend largely upon the tension in each spring and the alignment of the entire group. In this connection it is to be understood that each spring should have. a .definite tension in order to respond to a pedetermined current iow througlr the relay winding within the proper interval of time andin roper relation to the response of .other springs.. The tension in the individual springs will vary in accordancewiththrough t-he relay Winding, while in another.

the requirements of the relay in which they are employed. Thus, in one relay certain .of the springs may be required to release upon the passage of a predetermined current or the Vsame relay certain of the springs might be required to make( contact and exert a definite contact pressure when the relay is energized. Relays simulatingvthe one disclosed in the drawing which are employed in telephone circuits are often subjected to.

various adjustments, some being' required to operate on one current and to fall to operate 'on a `current j ust' slightly less, while others are -adjusted .to operate on a current slightly more. In' other words, eac'h spring mustr have a tension which meets the requirements of the particular-relay for wh'icli'it is employed, while the spring itself may be zo the ysame as used on other relays under different conditions.

' To insure the presence of a proper predetermined Itension in each of the Contact springs which are preferably constructed of -15 a non-ferrous spring-hard stock, such as nickel, silver or phosphorousfbronze, a plurality or series of depressions 26 are stamped or swaged'upon a surface of each of the contact springs, and these depressions may be 140 conveniently produced by the use. of a plut' spring 24 and a second die member 30- mayA rality of punching dies such as a die member 27 shown in Fig. 5 which lis provided with a plurality of cutting edges or teeth 29. `This \die member 27 may be placed'beneath the pressure by means of any suitable pressing device (not shown) causes the formation of depressions or indentations upon one surface of each of the contact springs and it is to be understood that'the spacing between the depressions formed in eachl of the contact sprm s orthe spacing between the die teeth, as we 1 as the depth of the depressions, will bedetermined by the amount of tension required by each contact spring in order to insure the proper functionin thereof. v

Altering the surface or sin of work-hardened springs in'an suitable manner such as the formation of epressions in the manner set forth, serves tocause the potential tension present within each spring to become effective. Thnat is, the breaking or altering of the skin on onel side of the spring will cause the -sprin to experience a bending tendency found to result from the releasing of the s'urface Aor skin tensiony and this bending tendenc is produced without subjecting the spring to a preliminary bending operation. Obviously, when the springs are closel mounted as shown' in the drawings, it 1s d1,- cult to bend themfar enough for the purpose of imparting a predetermined tension. `The fact that a springmay be produced having a predetermined tension by'employingl for this will be clear when it is observed that the contact spring 21 is of greater thickness than the spring 24 and hence the extent of the depressions made within the spring 21 must be greater than the extent of the depressions formed within the spring 24 in order to produce a corresponding increase in' Thus, the increase in tension protension. duced by the formation of depressions of a definite extent in a relatively thin spring, for example, may in some instances be as great as the increase in tension produced by the formation of depressions of much greater extent in a relatively thick spring. Each of the disclosed springs simulate cantilever beams and hence the tension of each spring will vary from the point of mounting where the greatest tension exists to the free ends thereof where the least ltension exists. Thus, it will be clear thatl in order to produce va predetermined increase in the tension in a spring of cantilever construction, the depressions formed therein must be greater in extent at the position approximating the mounted extremity of the spring. For this reason the depressions'26 formed at the left or mounted ends 0f the springs are greater in extent or length and decrease in graduated order in proportion to their distance from the mounted ends thereof. From the foregoing it will be understood that the invention contemplates the production of predetermined tensions in resilientv members such as contact springs by produclng alterations"or'depressions therein which are arranged in accordance with the tension desired and this arrangement is in turn dependent upon such factors as the relative thickness of the spring, the manner in which lll it is mounted, its shape and other physical characteristics. .Obviously alterations or depressions of varied forms may be employed a -to produce the desired results'and they may be produced on the spring surfaces by any l suitable means, This invention enables the of a pre etermined amount which has been pretensioning of contact springs in such.- a. manner as to make the invention particularly adaptable for use in connection with relays of the type disclosed in the drawings wherein the contact springs are secured in place and must be maintained in substantial parallelism and in -close proximity. In practice it has been found in one particular instance that in order to effect the proper functioning of the relay disclosed in the drawing, the contact springs 2l must be provided with a tension which will resist 'a force of approximately 35 gra-ms and the springs 23 and 24 must resist a force of approximately Q() grams. By employing die members provided with properly arranged and spaced teeth, such as the teeth 29 of the member 27 disclosed in Fig. 5, the above mentioned required amount of tension may be simultaneously produced within specified limit-s in all of the springs constituting each group Without impairing their parallel alignment. Obviously, the depth of the depressions made by the teeth of the die members may also be governed by the amount of compressive force to Whichl the parts are subjected. By interleaving the contact springs with die members in the manner described, a plurality of springs may be expeditiously pretensioned as distinguished from the time, manual eort and skill required in the individual treatment of the springs in each of the groups.

Although the invention has herein been described in connection with contact springs of cantilever construction used in a particular type of relay, it will be understood that the invention is capable of other applications and is only limited by the scope of the appended claims.

What is claimed is:

1. The method of producing a predetermined tension simultaneously in a plurality of contact springs, which consists in interleaving the springs with die members, and then applying pressure to produce indentations in pre etermined order on a surface of each spring.

2. The method of simultaneously producing in a plurality of spring members secured in close proximity to each other a mined tension in a plurality of superposed spring. members', which consists in interleaving the springs with die members having projections thereon, and then applying pressure to said springs and die members to cause said projections to form indent-ations on a surface of each spring.

4. The method of producing tension in a plurality of spring members mounted in superposed relation, which consists in interposing die members between adjacent spring members to form a pile, and then applying pressure to said pile to produce indentations upon the surfaces of said spring members.

5. The method of producing tension in a plurality of superposed spring members, each of said spring members having one of its ends ixedly mounted ina common mounting, which consists in interposing die members between adjacent spring members to form a pile, placing other die members at the top and bottoni of said pile, and then applying pressure to said die members and spring members to produce indentations upon the surfaces of said sprin members.

6. The method -o mined amounts of tension in a plurality of superposed contact springs, each of said springs having one of its ends lixedly mounted in a common mounting, which consists in placing die members between, above and below said spring members to form a pile, and then applying a predetermined pressure to said pile. to produce indentations upon the surfaces of said spring members.

In witness whereof, I hereunto subscribe my name this 28th day of March, A. D. 1927.

EARL VICTOR JOHNSON.

producing predeter- 

